Our goal in this project is to substantially improve the ability of magnetic resonance imaging (MRI) and angiography (MRA) to provide an unambiguous evaluation of the intracranial vasculature. This is a continuation of our long term objective to improve MRI/MRA to provide diagnostic information competitive to X-ray angiography in a manner that is safer and less expensive. Based upon the work of this and other projects, currently available MRA techniques have replaced many diagnostic X-ray angiography procedures. During the prior funding period (years 7 to 10), we have implemented several novel techniques to improve white blood and black blood intacranial MRA and have tested these as applied to the detection and management of intracranial aneurysms. Although white blood and black blood MRA have been substantially improved, both techniques have residual artifacts and ambiguities. White blood techniques still remain as the standard of care in most intracranial MRA applications. However, using a single image contrast is contrary to other diagnostic MRI procedures, such as evaluating parenchymal lesions, that typically rely on multiple types of image contrast to ensure accurate discrimination of normal and pathologic tissue. Our principle focus during the next funding period (years 11 to 15) will be to develop a novel composite set of MRI/MRA techniques, optimized on both 1.5T and 3.0T MRI scanners, yielding a set of multiple contrasts that collectively overcome ambiguities inherent in any individual technique. These techniques will provide isotropic high spatial resolution with sufficient signal to noise ratio (SNR). The acquisitions will be coupled with novel image registration, visualization, and analysis tools. The goal of this project is to determine an optimal and efficient combination of image contrasts necessary for an unambiguous evaluation of the intracranial vasculature. The value of these techniques will be assessed via application to a population of unruptured intracranial aneurysms, normal controls and eventually other disorders such as intracranial atherosclerosis.